Method for producing ethylene homo- and co-polymer

ABSTRACT

The present invention relates to a method for producing a polymer and copolymer of ethylene, and more particularly to a method for producing an ethylene polymer and copolymer by reacting a compound of an organic metal of Group II or m on the periodic table of elements with an alkoxy silane compound in the presence of a titanium catalyst, the said titanium catalyst being produced by a process of preparing a magnesium compound by contact-reacting a halogenated magnesium compound and alcohol, of reacting the said solution with an ester compound which contains at least one hydroxy group and a silicon compound containing an alkoxy group, and also of reacting it with a solid matter obtained by reaction of a mixture of a titanium compound and a silicon compound with a titanium compound. The catalyst used in polymerization and copolymerization of ethylene in the present invention is high in catalytic activity, and the polymer produced by the use of this catalyst has the merits of a high bulk density and a narrow molecular weight distribution.

TECHNICAL FIELD

[0001] The present invention relates to a method for preparing an ethylene polymer or copolymer, and more particularly a method for producing, by use of a catalyst of high activity, an ethylene polymer or copolymer with high bulk density and a narrow molecular weight distribution.

BACKGROUND ART

[0002] Magnesium-containing catalysts for production of ethylene polymer or copolymer are known to have very high catalytic activity and endow the produced polymer with a high bulk density. They are also known to be suitable for both liquid and gaseous reactions alike. The liquid polymerization of ethylene means the reaction taking place in the state of bulk ethylene or in a medium like isopentane and hexane, and in terms of the adaptability of a catalyst in such reactions its high activity and the resultant bulk density of a polymer are features of importance. A significant variable decisive of the properties of an ethylene polymer or copolymer, produced with the use of such a catalyst is the molecular weight distribution. Especially, a narrow molecular weight distribution is very advantageous in later manufacture of injection products.

[0003] Many catalysts containing magnesium and bases on titanium for production of olefin and the processes for production of these catalysts have been reported. In especial, many such processes as making use of magnesium solution to obtain catalysts for polymerization of olefin, which has a high bulk density, as has been mentioned above, have been learned. They include processes to obtain magnesium solutions by reacting magnesium compounds with such electron donors as alcohol, cyclic ether, organic carboxyl acid, etc. in the presence of hydrocarbon solvent. Instances where alcohol was used are referred to in U.S. Pat. Nos. 4,330,649 and 5,106,807. Methods for producing a magnesium-carrying catalyst by reacting a magnesium solution with such halogen compounds as titanium tetrachloride is well known. There have also been efforts to control the catalyst's activity and the polymer's molecular weight distribution by addition of ester compounds. These catalysts have a merit in providing the polymer's high bulk density, but their catalytic activity and the polymer's molecular weight distribution have something yet to be improved. Tetrahydrofuran, a cyclic ester, has been used as a magnesium compound solvent in U.S. Pat. Nos. 4,477,639 and 4,518,706.

[0004] Meanwhile, U.S. Pat. Nos. 4,847,639, 4,816,433, 4,829,037, 4,970,186, and 5,130,284 have reported use of such electron donors ad magnesium alkoxide, dialkylphthalate, phthaloyl chloride, etc. in reaction with a titanium chloride compound for production of catalysts with high catalytic activity and the resultant olefin's improved bulk density.

[0005] U.S. Pat. No. 5,459,116 has reported a method for production of a titanium-carrying solid catalyst by reacting a magnesium solution containing an ester having at least one hydroxy group as electron donor with a titanium compound. By this method it is possible to obtain a catalyst which, in excellent in catalytic activity, provides the resultant polymer with high bulk density, but the polymer has something yet to be improved in its molecular weight distribution.

[0006] Use of extraneous electron donors in polymerization of α-olefin, especially polyethylene, for improvement of stereoregularity is generally known, and it is, commercially, too, in the widest use. As extraneous electron donors alkoxysilane compounds are widely known, but it is also known that, although with the use of these the polymer's stereoregularity improves, generally its molecular weight distribution gets relatively broad. KP 93-665 has shown a way and its merit of rendering the polymer's molecular weight distribution narrower by the use of organic silane as extraneous electron donor in polymerization of propylene.

SUMMARY OF THE INVENTION

[0007] An objective of the present invention is to provide a method for production of an ethylene polymer or copolymer whose bulk density is large and the molecular weight distribution is narrow, and more particularly a method for producing thereby an ethylene polymer or copolymer of well-regulated granular forms, high polymerization activity, and a narrow molecular weight distribution.

[0008] The other objectives and usefulness of the present invention will also be clearly seen when its patent claims are looked into.

[0009] The process by the present invention for producing an ethylene polymer or copolymer is characterized in that it is produced by preparing a solid titanium complex catalyst in a simple yet effective process using magnesium, titanium, halogen, and an electron donor, viz. producing a magnesium compound solution by contact-reacting a halogenated magnesium compound and alcohol, reacting the said solution with an ester compound containing at least one hydroxy group and a silicon compound containing an alkoxy group, and adding thereto a mixture of a titanium compound and a silicon compound; and by performing an ethylene polymerization or copolymerization with a compound of an organic metal of Group II or III on the periodic table of elements by the use of the aforesaid catalyst in the presence of an alkoxy silane compound.

[0010] The kind of halogenated magnesium compounds which are used in production of the catalyst in the present invention may include such dihalogenated magnesiums as magnesium chloride, magnesium iodide, magnesium fluoride, and magnesium bromide; such alkylmagnesium halides as methylmagnesium halide, ethylmagnesium halide, propylmagnesium halide, butylmagnesium halide, isobutylmagnesium halide, hexylmagnesium halide, and amylmagnesium halide; such alkoxymagnesium halides as methoxymagnesium halide, ethoxymagnesium halide, isopropoxymagnesium halide, butoxymagnseium halide, and octoxymagnesium halide; and such aryloxymagnesium halides as phenoxymagnesium halide and methylphenoxymagnesium halide, for example. Of the above-named compounds, a mixture of two or more can also be used, and these magnesium compounds can also be effective when they are used in the form of a complex with other metals.

[0011] The above-listed compounds can be shown in simple chemical formulae, but exceptions arise from differences in the methods for producing the magnesium compounds. In such exceptional cases they generally can be regarded as mixtures of these listed magnesium compounds. For example, such can also be used in the present invention as the compounds obtained by reacting a magnesium compound with a polysiloxane compound, a halogen-containing silane compound, or alcohol; or the compounds obtained by reacting a magnesium metal with alcohol, phenol, or ether in the presence of halosilane, phosphor pentachloride, or thionyl chloride. The preferable magnesium compounds are magnesium halides, especially magnesium chloride and alkylmagnesium chloride, and still preferably those that have a C₁˜C₁₀ alkyl group; alkoxy magnesium chloride, preferably those that have a C₁˜C₁₀ alkoxy group, aryloxy magnesium chloride, preferably those that have a C₆˜C₂₀ aryloxy group. The magnesium solution used in the present invention can be made of the above-listed halogenated magnesium compounds by the use of alcohol in the presence or absence of a hydrocarbon solvent.

[0012] The kinds of hydrocarbon solvents which can be used here include, for example, such aliphatic hydrocarbons as pentane, hexane, heptane, octane, decane or kerosene; such alicyclic hydrocarbons as cyclobenzene, methylcyclobenzene, cyclohexane, or methylcyclohexane; such aromatic hydrocarbons as benzene, toluene, xylene, ethylbenzene, cumen, and cymene; and such halogenated hydrocarbons as dichloropropane, dichloroethylene, trichloroethylene, carbon tetrachloride, and chlorobenzene.

[0013] In conversion of the above-listed halogenated magnesium compounds into a magnesium compound solution, alcohol is used in the presence or absence of the above-listed hydrocarbons. The kinds of alcohol include such alcohols having 1˜20 carbons as methanol, ethanol, propanol, butanol, benzene alcohol, phenylethyl alcohol, isopropylenebenzyl alcohol, and cumyl alcohol; and preferably alcohols that have 1˜12 carbons. The desired size of granules of the catalyst and the preferable granular distribution in the resultant polymer vary according to the kinds and total quantity of alcohol, the kinds of magnesium compound, the ratio of magnesium to alcohol, etc., but the total quantity of alcohol required for use to obtain the necessary magnesium solution is at least 0.5 mol, preferably about 1.0˜20 mols, and more preferably about 2.0˜10 mols to one mol of the magnesium compound.

[0014] The reaction of a halogenated magnesium compound and alcohol in production of the magnesium compound solution is performed preferably in a hydrocarbon medium for about 15 minutes to five hours, preferably for about 30 minutes to four hours, at about −25° C., preferably −10˜200° C., and more preferably at about 0˜150° C., though the temperature may vary according to the kind and quantity of alcohol in use.

[0015] Among the ester compounds used as electron donors in production of the catalyst in the present invention, those having at least one hydroxy group include, for example, such unsaturated aliphatic acid esters containing at least one hydroxy group as 2-hydroxy ethylacrylate, 2-hydroxy ethylmethacrylate, 2-hydroxy propylacrylate, 2-hydroxy propylmethacrylate, 4-hydroxy butylacrylate, and pentaerythritol triacrylate; such aliphatic monoesters and polyesters containing at least one hydroxy group as 2-hydroxy ethylacetate, methyl 3-hydroxy butylate, ethyl 3-hydroxy butylate, methyl 2-hydroxy isobutylate, ethyl 2-hydoxy isobutylate, methyl-3-hydroxy-2-methyl propionate, 2,2-dimethyl-3-hydroxy propionate, ethyl-6-hydroxy hexanoate, t-butyl-2-hydroxy isobutylate, diethyl-3-hydroxy glutarate, ethyl lactate, isopropyl lactate, butylisobutyl lactate, isobutyl lactate, ethylmandelate, dimethyl ethyl tartrate, ethyl tartrate, dibutyl tartrate, diethyl citrate, triethyl citrate, ethyl 2-hydroxy caproate, or diethyl bis-(hydroxy methyl) malonate; such aromatic esters containing at least one hydroxy group as 2-hydroxy ethyl benzoate, 2-hydroxy ethyl salicylate, methyl 4-(hydroxy methyl) benzoate, methyl 4-hydroxy benzoate, ethyl 3-hydroxy benzoate, 4-methyl salicylate, ethyl salicylate, phenyl salicylate, propyl 4-hydroxy benzoate, phenyl 3-hydroxy naphthenoate, monoethylene glycol monobenzoate, diethylene glycol monobenzoate, and triethylene glycol monobenzoate; and such alicyclic esters containing at least one hydroxy group as hydroxy butyl lactone. The required quantity of any of these monoester compounds having at least one hydroxy group is 0.001˜5 mols, preferably 0.01˜2 mols to one mol of magnesium.

[0016] For the silicon compound containing an alkoxy group, which can be used as another electron donor in production of the catalyst in the present invention, a compound which is represented by the general formula: R¹ _(n)Si(OR²)_(4-n) (here R¹ and R² are hydrocarbons having 1˜12 carbons, while “n” a natural number from 0 to 3) is preferable. In particular, such compounds can be used as dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane, methylphenyldimethoxysilane, diphenyldiethoxysilane, ethyltrimethoxysilane, vinyltrimethoxysilane, methyltrimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, vinyltriethoxysilane, butyltriethoxysilane, phenyltriethoxysilane, ethyltriisopropoxysilane, vinyltributoxysilane, ethylsilicate, butylsilicate, methyltriaryloxysilane, etc. The required quantity of these compounds is preferably 0.05˜3 mols, and more preferably 0.1˜2 mols, to one mol of magnesium.

[0017] The temperature for contact-reaction of the liquid magnesium compound with the compound having at least one hydroxy group and the ester compound having an alkoxy group is preferably 0˜100° C., and more preferably 10˜70° C.

[0018] The magnesium compound solution which has been reacted with an electron donor is then, for crystallization of the catalyst' particles, reacted with a mixture of a liquid titanium compound represented by the general formula Ti(OR)_(a)X_(4-a) (here “R” is a hydrocarbon group having 1 to 10 carbons, “X” a halogen atom, “a” a natural number from 0 to 4) and a silicon compound represented by the general formula R_(n)SiCl_(n-4) (here “R” is hydrogen, an alkyl group having 1˜10 carbons, an alkoxy, haloalkyl, aryl group, or halosillyl having 1˜8 carbons, or a halosillylalkyl group, and “n” a natural number from 0 to 4).

[0019] The kind of titanium compounds which satisfy the above general formula Ti(OR)_(a)X_(4-a) includes, for example, such tetrahalogenated titaniums as TiCl₄, TiBr₄, and TiI₄; such tri-halogenated alkoxy titaniums as Ti(OCH₃)Cl₃, Ti(OC₂H₅)Cl₃, Ti(OC₂H₅)Br₃, and Ti(O(i-C₄H₃)Br₃; such dihalogenated alkoxy titaniums as Ti(OCH₃)₂Cl₂, Ti(OC₂H₅)₂Cl₂. Ti(O(i-C₄H₉))₂Cl₂, and Ti(OC₂H₅)₂Br₂; and such tetraalkoxy titaniums as Ti(OCH₃)₄, Ti(OC₂H₅)₄, or Ti(OC₄H₉)₄. Mixtures of the above titanium compounds can also be used in the present invention. The preferable titanium compounds are halogen-containing compounds, and the more preferable are titanium tetrachlorides.

[0020] The silicon compounds which satisfy the above general formula R_(n)SiCl_(n-4) include, for example, silicon tetrachloride, such trichlorosilanes as methyltrichlorosilane, ethyltrichlorosilane, and phenyltrichlorosilane, such dichlorosilanes as dimethyldichlorosilane, diethyldichlorosilane, diphenyldichlorosilane, and methylphenyldichlorosilane, and such a monochlorosilane as trimethylchlorosilane. Mixtures of these silicon compounds can also be used. The preferable silicon compound is silicon tetrachloride, however.

[0021] The quantity of the mixture of a titanium compound and a silicon compound used for crystallization of the magnesium compound solution is preferably 0.1˜200 mols to one mol of the magnesium compound, preferably 0.1˜100 mols, and more preferably 0.2˜80 mols. The molar ratio of titanium compound and silicon compound in the mixture is adequately 0.05˜0.95, or more preferably 0.1˜0.8. The shape and size of the crystallized solid constituent vary according to the conditions at the time of reaction of the magnesium compound solution and the mixture of titanium and silicon compounds. Therefore, the reaction of the magnesium compound solution and the mixture of titanium and silicon compounds is performed at a sufficiently low temperature, for formation of the solid constituent, preferably a contact-reaction at −70° C.˜70° C., more preferably at −50° C.˜50° C. After the contact-reaction, the temperature is gradually raised and the reacti9on is let to continue at 50° C.˜150° C. for 0.5 hour to five hours.

[0022] The solid complex catalyst particles thus obtained may be further reacted with a titanium compound. The titanium compound for this further reaction is preferably a titanium halide, or a halogenated alkoxy titanium containing 1˜20 carbons of an alkoxy functional group. A mixture of these may at times be used. Of these, titanium halide and halogenated titanium having 1˜8 carbons of an alkoxy functional group are the more preferable, and yet more preferable is titanium tetrahalide.

[0023] The solid titanium catalyst prepared by a method of the present invention is profitably used in polymerization and copolymerization of ethylene. In especial, it is used in homo-polymerization of ethylene and copolymerization of ethylene with such α-olefin having three or more carbons as propylene, 1-butane, 1-pentane, 4-methyl-1-pentane, and 1-hexane.

[0024] The polymerization reaction in the present invention is for preparation of ethylene polymers or copolymers with the use of (1) the aforesaid solid titanium catalyst made from magnesium, titanium, and halogen, along with an electron donor, and (2) a compound of an organic metal of Group II or III on the periodic table of elements, (3) in the presence of an alkoxy silane compound as extraneous electron donor.

[0025] The aforesaid solid titanium catalyst can also be pre-polymerized in ethylene or α-olefin, prior to use as constituent in a polymerization reaction. The pre-polymerization can be performed in the presence of a hydrocarbon solvent like hexane or else at a sufficiently low temperature and under the pressure conditions of ethylene or α-olefin in the presence of the aforesaid catalyst constituents and such an organic aluminum compound as triethylaluminum. Pre-polymerization makes catalyst granules wrapped in polymers to maintain the shape of the catalyst and thus helps to better the shape of the polymer after polymerization. The ratio in weight of polymer to catalyst after the pre-polymerization is usually 0.1:1˜20:1.

[0026] The organic metal compound useful in the present invention can be represented by the general formula: MR_(n). Here “M” stands for such metals of Groups II and III on the periodic table of elements as magnesium, calcium, zinc, boron, aluminum or gallium; “R” for such alkyl groups having 1 to 20 carbons as methyl, ethyl, butyl, hexyl, octyl, or decyl; “n” for the valences of metals. For the more preferable organic metal compounds such trialkylaluminums containing an alkyl group of 1 to six carbons as triethylaluminum and triisobutylaluminum and their mixtures are commendable. In some cases such organic aluminum compounds containing one or more halogen or hydride groups as ethylaluminum dichloride, diethylaluminum chloride, ethylaluminum sesquichloride, or diisobutylaluminum hydride can be used. Mixtures of these organic metal compounds are also usable.

[0027] Generally, to secure the catalyst's best activity and the resultant polymer's best stereo-regularity in polymerization of α-olefin, and especially of propylene, many extraneous electron donors are used. They include such organic compounds containing atoms of oxygen, silicon, nitrogen, sulfur, and phosphorus as organic acid, organic acid anhydride, organic acid ester, alcohol, ether, aldehyde, ketone, silane, amine, amine oxide, amide, diol, and ester phosphate, along with mixtures of these. The electron donors useful in preparation of the ethylene polymers having a narrow molecular weight distribution, in the present invention, organic silicon compounds having an alkoxy group, viz. alkoxy silane compounds, and these can be represented by a general formula: SiOR⁴), “R” here indicating alky groups containing 1˜20 carbons. The kind includes such aromatic silanes as diphenylmethoxysilane, phenyltrimethoxysilane, phenylethylmethoxysilane, phenylmethyldimethoxysilane; such aliphatic silanes as isobutyltrimethoxysilane, diisobutyldimethoxysilane, diisopropyldimethoxysilane, di-t-butyldimethoxysilane, t-butyltrimethoxysilane, cyclohexylmethyldimethoxysilane, dicyclopentyldimethoxysilane, dicyclohexyldimethoxysilane, 2-novonantriethoxysilane, vinyltriethoxysilane; and their mixtures. In especial, of these silane compounds, such a magnetized alkylalkoxysilane as diisobutyldimethoxysilane and such cycloalkyldialkoxysilane as dicyclopentyldimethoxysilane have proved effective.

[0028] The polymerization reaction in the present invention is performed in the gaseous phase or in bulk in the absence of an organic solvent, or else in a condition of liquid slurry in the presence of an organic solution. The reactions, however, are performed in the absence of oxygen, water, or any compounds that may act as catalytic poison.

[0029] In the case of liquid slurry polymerization, the preferable concentration of the solid titanium catalyst (1), in the group of polymerization catalysts, is about 0.001˜5 Mmols in terms of the number of the titanium atoms against one liter of the solvent, more preferably about 0.001˜0.5Mmols. For the solvent, such alkanes or cycloalkanes, as pentane, hexane, heptane, n-octane, isooctane, cyclohexane, and methylcyclohexane; such alkylaromatics as toluene, xylene, ethylbenzene, isopropylbenzene, ethyltoluene, n-propylbenzene, and diethylbenzene; and such halogenated aromatics as chlorobenzene, chloronaphthalene, or orthodichlorobenzene; and mixtures of these, can be useful.

[0030] In the case of gaseous polymerization the quantity of the solid titanium catalyst (1) is, in terms of the number of titanium atoms in the catalyst to a liter of polymerization, about 0.001˜5 Mmols, preferably about 0.001˜1.0 Mmols, still preferably about 0.01˜0.5 Mmols.

[0031] The preferable concentration of the organic metal compound (2) is about 1˜2000 mols, more preferably about 5˜500 mols, in terms of the number of the atoms of the organic metal to one mol of the titanium atoms in the catalyst (1).

[0032] The concentration of the alkoxy silane compound (3) is preferably 0.01˜40 mols and more preferably about 0.05˜30 mols in terms of the number of the silicon atoms to one mol of the organic metal's atoms in the organic metal compound.

[0033] To secure a high speed in polymerization the reaction is performed at a sufficiently high temperature regardless of the polymerization process itself. Generally, about 20˜200° C. are adequate, and more preferably 20˜95° C. The pressure of a monomer is adequately the atmospheric to 100 atm, and more preferably 2˜50 atm.

[0034] The molecular weighs of the polymer in the present invention are given in terms of the generally broadly known ASTM D 1238. In ASTM, the smaller the molecular weights are the larger the values are shown. Meanwhile, the molecular weight distribution was obtained through measurement by GPC (Gel Permeation Chromatography), the measurement method having been the one generally widely adopted in the field.

[0035] What has been obtained in the present invention solid ethylene monomers and copolymers of ethylene and α-olefin, the recovery rate being sufficiently high, making separate treatment for removal of the dregs of the catalyst unnecessary. High bulk density and flowage are also gained all right.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0036] The present invention is described in further detail below through the embodiment examples and comparative examples, but the present invention should never be construed to be limited or confined to these examples.

EXAMPLE 1

[0037] Production of the Catalyst

[0038] A solid complex titanium catalyst was prepared through the following three steps:

[0039] Step (i): Production of a magnesium solution

[0040] Into a 1.0-liter reactor equipped with a mechanic stirrer, converted into nitrogenous atmosphere, 9.5 g of MgCl₂ and 500 ml of decane were put and stirred at 500 rpm, 72 ml of 2-ethylhexane was added thereto, the temperature was raised to 110° C., and the reaction was let to continue for three hours. The homogeneous solution obtained by the reaction this way was cooled to normal temperature (25° C.).

[0041] Step (ii): Contact-reaction of the magnesium solution with ester containing a hydroxy group and a silicon compound containing an alkoxy group

[0042] To the said magnesium solution cooled to normal temperature were added 1.4 ml (10 Mmols) of 2-hydroxyethylmethacrylate and 10.0 ml (45 Mmols) of silicon tetraethoxide, and the solution was left to react for one hours.

[0043] Step (iii): Treatment with a mixture of a titanium compound and a silicon compound

[0044] The above solution was adjusted to room temperature (25° C.), and to it a mixture of 70 ml of titanium tetrachloride and 70 ml of silicon tetrachloride was dripped for two hours. After the dripping, the reactor was heated to 80° C., taking one hour, while getting stirred, and then kept at that temperature for another hour. The stirring was stopped, and the solution at the top was separated, and to the solid layer left behind 300 ml of toluene and 100 ml of titanium tetrachloride were instilled in continuation, the temperature was raised to 100° C. and kept there for two hours. After the reaction the reactor was cooled to room temperature, and washed in 400 ml of hexane until the remaining unreacted titanium tetrachloride was completely removed. The titanium content of the thus prepared solid catalyst was 4.7%.

[0045] Polymerization

[0046] After a 2-liter high pressure reactor was dried in an oven, it was assembled while it was hot, and then by alternating treatments with nitrogen and evacuation for three times the inside of the reactor was converted into nitrogenous atmosphere. 1,000 ml of n-hexane was put into the reactor, and 2 Mmols of triethylaluminum, 0.1 Mmol of dicyclohexylmethyldimethoxysilane, and 0.03 Mmol of the solid catalyst in terms of the number of titanium atoms, were instilled, and 2,000 ml of hydrogen was instilled. As the reactor was agitated by 700 rpm, the temperature of the reactor was raised to 80° C., and after the pressure of ethylene was adjusted to 120 psi, polymerization was continued for one hour. After the polymerization, the reactor was cooled to room temperature, and a small amount of ethanol was added to the polymerized. The thus prepared polymer was then collected by separation, dried in a vacuum oven at 50° C. for at least six hours, finally to obtain polyethylene in the form of white powder.

[0047] The polymerization activity (kg polyethylene/g catalyst) was calculated in terms of the ratio of the weight (g) of the used catalyst to the produced polymer (kg). The results of the polymerization along with the bulk density (g/ml), melting index, and molecular weight distribution are shown in Table 1.

EXAMPLE 2

[0048] Using the catalyst prepared in Example 1, polymerization was carried out in the same way as Example 1 with the only exception that 0.1 Mmol of dicyclopentyldimethoxysilane was used instead of dicyclohexylmethyldimethoxysilane. The results are given in Table 1.

EXAMPLE 3

[0049] Using the catalyst prepared in Example 1, polymerization was carried out in the same way as Example 1 with the only exception that 0.1 Mmol of diisopropyldimethoxysilane was used instead of dicyclohexylmethyldimethoxysilane. The results are given in Table 1.

EXAMPLE 4

[0050] Using the catalyst prepared in Example 1, polymerization was carried out in the same way as Example 1 with the only exception that 0.1 Mmol of phenyltriethoxysilane was used instead of dicyclohexylmethyldimethoxysilane. The results are given in Table 1.

EXAMPLE 5

[0051] Using the catalyst prepared in Example 1, polymerization was carried out in the same way as Example 1 with the only exception that 0.1 Mmol of propyltriethoxysilane was used instead of dicyclohexylmethyldimethoxysilane. The results are given in Table 1.

EXAMPLE 6

[0052] Using the catalyst prepared in Example 1, polymerization was carried out in the same way as Example 1 with the only exception that 0.1 Mmol of t-butyltriethoxysilane was used instead of dicyclohexylmethyldimethoxysilane. The results are given in Table 1.

EXAMPLE 7

[0053] Using the catalyst prepared in Example 1, polymerization was carried out in the same way as Example 1 with the only exception that 0.5 Mmol of dicyclopentyldimethoxysilane was used instead of dicyclohexylmethyldimethoxysilane. The results are given in Table 1.

EXAMPLE 8

[0054] Using the catalyst prepared in Example 1, polymerization was carried out in the same way as Example 1 with the only exception that 0.3 Mmol of dicyclopentyldimethoxysilane was used instead of dicyclohexylmethyldimethoxysilane. The results are given in Table 1.

EXAMPLE 9

[0055] Using the catalyst prepared in Example 1, polymerization was carried out in the same way as Example 1 with the only exception that 1,000 ml of hydrogen was used in the process for polymerization. The results are given in Table 1.

EXAMPLE 10

[0056] Using the catalyst prepared in Example 1, polymerization was carried out in the same way as Example 1 with the only exception that 3,000 ml of hydrogen was used in the process for polymerization. The results are given in Table 1.

COMPARATIVE EXAMPLE 1

[0057] Polymerization was carried out in the same way as in Example 1 with the only exception that the catalyst prepared in Example 1 and dicyclohexylmethyldimethoxysilane were not used in the process of polymerization in Example 1. The results are given in Table 1.

COMPARATIVE EXAMPLE 2

[0058] Catalyst was produced without using 2-hydroxyethylmethacrylate and silicon tetraethoxide in Step (ii) of the process for preparing the catalyst in Example 1. The content of titanium in the thus produced catalyst was 4.7%. Polymerization was carried out under the same condition as Example 1, the results being given in Table 1.

COMPARATIVE EXAMPLE 3

[0059] Catalyst was produced using 10 ml of silicon tetraethoxide but not 2-hydroxyethylmethacrylate in Step (ii) of the process for preparing the catalyst in Example 1. The content of titanium in the thus produced catalyst was 4.5%. Polymerization was carried out under the same conditions as Example 1, the results being given in Table 1.

COMPARATIVE EXAMPLE 4

[0060] Catalyst was produced using 1.4 ml of 2-hydroxyethyl-methacrylate but not silicon tetraethoxide in Step (ii) of the process for preparing the catalyst in Example 1. The content of titanium in the thus produced catalyst was 4.4%. Polymerization was carried out under the same conditions as Example 1, the results being given in Table 1. TABLE 1 Polymerization Results Molecular Weight Bulk Density Melting Index Distribution Examples Activity* (g/ml) (g/10 min) (Mw/Mn) 1 10.9 0.39 4.2 4.1 2 11.6 0.38 4.1 3.9 3 11.2 0.37 4.3 3.7 4 10.8 0.38 3.9 4 5 10.6 0.39 4.4 4.3 6 10.9 0.38 4.2 4.3 7 12.7 0.37 4.6 3.9 8 10.9 0.4 3.7 3.6 9 14.7 0.37 0.7 4.1 10  7.9 0.4 15.7 3.9 Comp 1 9.7 0.37 4.8 6.5 Comp 2 7.7 0.32 1.7 5.8 Comp 3 8.2 0.34 1.9 6.1 Comp 4 9 0.33 2.8 5.7

[0061] As shown in the table above, it has been possible to obtain, by the method in the present invention, a catalyst of high catalytic activity as well as ethylene polymers and copolymers having high bulk density and a narrow molecular weight distribution. 

What is claimed is:
 1. A method of producing ethylene homo- or co-polymers, which comprises: (a) producing a solid titanium catalyst by: (i) producing a magnesium compound solution by contact-reacting a mixture of a halogented magnesium compound with alcohol; (ii) reacting said solution with an ester compound having at least one hydroxy group, and a silicon compound having alkoxy groups; and (iii) reacting a titanium compound with the solid component obtained from reacting a mixture of a titanium compound and a silicon compound thereto; and (b) polymerizing with said solid titanium catalyst, and an organometallic compound of Group II and II of the Periodical Table, (c) in the presence of an alkoxysilane compound.
 2. The method of producing ethylene homo- or co-polymers according to claim 1, wherein said ester compound having at least one hydroxy group is an unsaturated aliphatic acid ester having at least one hydroxy group, which is selected from the group consisting of 2-hydroxy ethylacrylate, 2-hydroxy ethylmethacrylate, 2-hydroxy propylacrylate, 2-hydroxy propylmethacrylate, 4-hydroxy butylacrylate, pentaerithritol triacrylate; an aliphatic monoester or polyester having at least one hydroxy group, which is selected from the group consisting of 2-hydroxy ethyl acetate, methyl 3-hydroxy butylate, ethyl 3-hydroxy butylate, methyl 2-hydroxy isobutylate, ethyl 2-hydroxy isobutylate, methyl-3-hydroxy-2-methyl propionate, 2,2-dimethyl-3-hydroxy propionate, ethyl-6-hydroxy hexanoate, t-butyl-2-hydroxy isobutylate, diethyl-3-hydroxy glutarate, ethyl-lactate, isopropyl lactate, butyl-isobutyl lactate, isobutyl lactate, ethyl mandelate, dimethyl ethyl tartrate, ethyl tartrate, dibutyl tartrate, diethyl citrate, triethyl citrate, ethyl-2-hydroxy-caproate, diethyl bis-(hydroxymethyl) malonate; an aromatic ester having at least one hydroxy group, which is selected from the group consisting of 2-hydroxy ethyl benzoate, 2-hydroxy ethyl salicylate, methyl-4-(hydroxy methyl) benzoate, methyl-4-hydroxy benzoate, ethyl-3-hydroxy benzoate, 4-methyl salicylate, ethyl salicylate, phenyl salicylate, propyl-4-hydroxy benzoate, phenyl-3-hydroxy naphthanoate, monoethylene glycol monobenzoate, diethylene glycol monobenzoate, triethylene glycol monobenzoate; or an alicyclic ester compound having at least one hydroxy group as in hydroxy butyl-lactonel; and wherein said silicon compound having alkoxy groups is a compound of a general formula of R¹ _(n)Si(OR²)_(4-n), in which R¹ and R¹ respectively are hydrocarbon groups having 1˜12 carbon atoms, and n is a natural number of 0˜3, in which said silicon compound is selected from the group consisting of dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane, methylphenylmethoxysilane, diphenyldiethoxysilane, ethyltrimethoxysilane, vinyltrimethoxysilane, methyltrimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, vinyltriethoxysilane, butyltriethoxysilane, phenyltriethoxysilane, ethyltriisopropoxysilane, vinyltributoxysilane, ethylsilicate, butylsilicate, or methyltriaryloxylsilane.
 3. The method of producing ethylene homo- or co-polymers according to claim 1, wherein said titanium compound is represented by a general formula of Ti(OR)_(a)X_(4-a), in which R is an alkyl group having 1˜10 carbon atoms, with X for a halogen atom, and a for an integer of 0˜4; and wherein said silicon compound is represented by a general formula of R_(n)SiCl_(n-4), in which R is hydrogen, an aryl, alkoxy, haloalkyl or alkyl group having 1˜10 carbon atoms, or a halosilylalkyl or halosilyl group having 1˜8 carbon atoms, and n for an integer of 0˜4.
 4. The method of producing ethylene homo- or co-polymers according to claim 3, wherein said titanium compound is a 4-halogenated titanium, which is selected from the group consisting of TiCl₄, TiBr₄, and TiI₄; a 3-halogenated alkoxytitanium, which is selected from the group consisting of Ti(OCH₃)Cl₃, Ti(OC₂H₅)Cl₃, Ti(OC₂H₅)Br₃, and Ti(O(i-C₄H₉)Br₃; a 2-halogenated alkoxytitanium, which is selected from the group consisting of Ti(OCH₃)₂Cl₂, Ti(OC₂H₅)₂Cl₂, Ti(O(i-C₄H₉)₂)Cl₂, and Ti(OC₂H₅)₂Br₂; and a tetralkoxy titanium, which is selected from the group consisting of Ti(OCH₃)₄, Ti(OC₂H₅)₄, and Ti(OC₄H₉)₄; and wherein said silicon compound is silicon tetrachloride; or a trichlorosilane, which is selected from the group consisting of trichlorosilane, methyltrichlorosilane, ethyltrichlorosilane, and phenyl-trichlorosilane; a dichlorosilane, which is selected from the group consisting of dimethylchlorosilane, diethyldichlorosilane, diphenyldichlorosilane, and methylphenyldichlorosilane; or a monochlorosilane as in trimethylchlorosilane.
 5. The method of producing ethylene homo- or co-polymers according to claim 3, wherein said titanium compound is titanium tetrachloride, and said silicon compound is silicon tetrachloride.
 6. The method of producing ethylene homo- or co-polymers according to claim 1, wherein said alkoxysilane compound is a compound represented by a general formula of SiOR⁴, in which R is an alky group having 1˜20 carbons, which is a aromatic silane, selected from the group of diphenylmethoxysilane, phenyltrimethoxysilane, phenylethylmethoxysilane, and phenylmethyldimethoxysilane; an aliphatic silane, which is selected from the group consisting of isobutyltrimethoxysilane, diisobutyldimethoxysilane, diisopropyldimethoxysilane, di-t-butyldimethoxysilane, t-butyltrimethoxysilane, cyclohexylmethyldimethoxysilane, dicyclopentyldimethoxysilane, dicyclohexyldimethoxysilane, 2-novonantriethoxysilane, 2-novonanmethyldimethoxysilane, vinyltriethoxysilane; or the mixtures thereof. 